Hook & Loop fastening system made with aluminum oxide grain. Resin coated to resist heat and humidity for longer life. Fits: Random Orbit Sanders. Applications: Wood, Metal, Fiberglass, Plastic & Painted Surfaces. Amazon.com The Porter-Cable 735802205 5-Inch 220 Grit Eight-Hole Hook and Loop Sanding Discs are designed to meet the highest standards for today's woodworker and construction professionals. Made with aluminum oxide grain, and resin coated to resist heat and humidity, these 220-grit discs feature an anti-clog coating that resists unwelcome loading. Made for durability and performance, these discs can be used on wood, metal fiberglass, plastic and painted surfaces